CHAPTER 3 Anette Overland Department of Natural History, University Museum, University of Bergen, Norway [email protected] KARI LOE HJELLE Department of Natural History, University Museum, University of Bergen, Norway Vegetation development at Ørland, and in the region, from c. 260 BC to the present ABSTRACT The vegetation history at Ørland is based on pollen analysis of a local bog (Ryggamyra), and several archaeological contexts, such as cultivation layers and plow mark, a refuse/cesspit, and wells and waterholes. Ryggamyra reflects important activity periods, in the Pre-Roman Iron Age and Roman Iron Age, where barley was cultivated and areas with herbaceous grasslands existed in connection with settlement areas. In comparison, pollen analysis from lake sediments (Eidsvatnet) reflects a larger region. Eidsvatnet covers the period c. 260 BC to the present, during which three periods of more intensive human activity can be identified, when forest is cleared, grass-dominated vegetation increases, and outfield grazing areas are established. These periods are the Roman Iron Age and Migration Period (c. AD 1-540), parts of the Viking Age and Early and High Middle Ages (c. AD 900–1360), and recent times (from AD 1600 onwards). In both pollen profiles, Eidsvatnet and Ryggamyra, the Merovingian period represents a period with structural changes in landscape utilization and perhaps less human activity overall. Ørland has largely been characterized by marshes and wetland areas through the past, dominated by Cyperaceae. On the drier main ridge, where settlement areas existed in the Pre-Roman Iron Age and Roman Iron Age, and again in the early medieval period, the pollen profiles indicate a completely open landscape with herb-rich grassy vegetation and cultivation of barley and wheat. The increase in heather from the Late Viking Age to the early medieval period is seen in Ryggamyra and is reflected in the archaeological deposits, indicating utilization of heathlands for whole-year grazing. Pollen analysis also suggests local production/use of hemp and increased use of wheat in medieval times. The area around Eidsvatnet seems to be influenced by the late medieval depression and Black Death, with the increase in coniferous woodland and reduced outfield grazing activity. INTRODUCTION activity seems to have been during Pre-Roman Archaeological excavations at Ørland Main Air Base, and Roman Iron Age, with several house remains, carried out by NTNU Science Museum 2014–2016, cooking pits and different deposits reflecting farm revealed settlements from the Bronze Age/Iron Age settlements. Pollen samples were collected from transition through the Early Iron Age, followed by archaeological contexts including cultivation layers, a new phase of settlement in the Late Viking Age/ plow marks, refuse/cesspits, wells and waterholes. Middle Ages. At the transition Early/Late Iron The aims of the pollen analysis were to provide Age, the archaeological data are scarce. The highest knowledge on environment, natural conditions, 69 Environment and settlement | Anette Overland – KARI LOE HJELLE Figure 1. Localities for pollen analysis. Eidsvatnet (lake), Ryggamyra (bog) and archaeological contexts in excavation Field A (152149), Field D (616154, 616349/616346, 616158) and Field E (223883, 224758/224324, 222721, 223002, 223668), (See Buckland et al. (2017) for pollen analysis of 151397, 337695, 337696, 338506). Map: Magnar Mojaren Gran, NTNU University Museum. 70 Vegetation development at Ørland, and in the region, from c. 260 BC to the present landscape development, settlement and farming burning and grazing (Kaland 1986, 2014). They are economy at Ørland. The investigation also included found in an oceanic climate, giving possibilities pollen analysis of a local peat profile, Ryggamyra, for whole-year grazing. In historic time, they have and sediments from the lake Eidsvatnet (Fig. 1). characterized the western coast of Norway, but the Ryggamyra represents a local palaeobotanical archive, development spans over several thousand years and which will reflect the development of the environ- shows large variations along the coast (Kaland 1986, ment and landscape at Ørland, as well as human Prøsch-Danielsen & Simonsen 2002, Tveraabak impact on the local vegetation and landscape. Pollen 2004, Hjelle et al. 2010, 2018). Ørland is located analysis of sediments from Eidsvatnet, which is within the coastal heathland belt, and our study situated approximately 10.5km from Ryggamyra gives new information on their history in relation and the archaeological excavation areas, will provide to settlement in this part of Norway. the regional setting for landscape and vegetation development. Earlier studies from Ørland include MATERIAL AND METHODS analysis of pollen samples from bogs at Borgestad and Veklem. At Borgestad, c. 5.5km east of the Samples and radiocarbon dates excavation area, the development of an open cul- The sediment core from Eidsvatnet (63.7388N, tural landscape with cultivation and grazing in the 9.8375E, 64ha, Fig. 1) was collected by NGU Late Bronze Age and Early Iron Age, is indicated (Geological Survey of Norway) (Romundset & (Solem 2009). Pollen analysis from a small bog at Lakeman Ch. 2). Pollen samples (volume 1cm3) Veklem close to Ørland church reveals an open were collected at NGU, every 0.5cm continuously landscape from the Late Bronze Age (Berglund through the core. Loss-on-ignition was done on the & Solem 2017). At that site, cultivation is docu- sample directly below the analyzed pollen sample. mented from the Middle Ages whereas grazing The isolation of the lake is radiocarbon dated to was found from the Iron Age. Also a few pollen c. 2200 cal. yr BP while two dates from the top samples previously analyzed from Field D at Vik of the core (838–839cm, Poz-86900/86901) gave (Engtrø & Haug 2015) indicated open arable fields modern age (Table 1). Based on the radiocarbon and grasslands in Pre-Roman and Roman Iron Age. dates (Table 1) and the age 1950 given to the Except for these investigations, all made in relation upper dated level, an age-depth model is presented to archaeological projects, no investigation of the (Fig. 2). Sediment stratigraphy is shown in Table 2. vegetation history at Ørland has earlier been carried Eidsvatnet is located 10.5km east of the archaeo- out. However, the Holocene vegetation history is logical excavation areas. well documented at the island Frøya, c. 44km west The bog Ryggamyra (id 282408, 63.7185N, of Ørland (Paus 1982). Contemporary with the 9.6355E, 4ha, Fig. 1) is situated on the central settlement at Ørland, open heathlands managed ridge of the peninsula which first became exposed through grazing and burning characterized the above sea level around 2400 years ago (Romundset landscape of Frøya. On the islands outside Ørland & Lakeman ch. 2), and is situated c. 1000m north of (incl. Tarva), there is evidence of at least 300 years the archaeological excavation areas. A bog monolith of managed heathland (Kaland & Kvamme 2013). was extracted and subsampled for pollen analysis Coastal heathlands represent a human-induced (sample volume 1cm3) and loss-on-ignition in the vegetation type developed and maintained through laboratory at the University of Bergen. Radiocarbon 71 Environment and settlement | Anette Overland – KARI LOE HJELLE Lab. ID C14-age, calibration (2σ) Depth (cm) Dated material Eidsvatnet. Depth: from water surface 137.67±0.33 pMC (’percent Poz-86900 838–839 Wooden twig modern carbon’) 140.44±0.35 pMC (’percent Poz-86901 838–839 Terrestrial plant fragments modern carbon’) Terrestrial plant fragments, Beta-467912 480±30 BP, Cal. AD 1409–1451 851–852 chironomids Beta-467913 1160±30 BP, Cal. AD 774–967 864–865 Wood fragment Beta-467914 1520±30 BP, Cal. AD 428–608 877–878 Wooden twig Beta-469526 1780±30 BP, Cal. AD 138–333 884–885 Seed Poz-86867 1705±30 BP, Cal. AD 253–400 885–886 Terrestrial plant fragments Poz-86868 2130±30 BP, 349–53 Cal. BC 896–897 Terrestrial plant fragments Poz-86869 2125±30 BP, 346–53 Cal. BC 899–900 Terrestrial plant fragments Poz-86870 2170±30 BP, 359–118 Cal. BC 902–903 Betula fruit and leaf fragment Ryggamyra (282408). Depth: from peat surface Beta-474786 620±30 BP, Cal. AD 1292–1400 79–80 Terrestrial plant fragments Poz-1116326 1045±30 BP, Cal. AD 901–1029 110-111 Terrestrial plant fragments Beta-451876 1150±30 BP, Cal. AD 773–970 120–121 Terrestrial plant fragments TRa-11515 1440±20 BP, Cal. AD 584–649 129–130 Terrestrial plant fragments Beta-451877 2340±30 BP, 506–367 Cal. BC 153–154 Terrestrial plant fragments Field A (152149). Depth: from base of monolith Beta-474785 850±30 BP, Cal. AD 1152–1260 34.5–48.5 Charcoal TRa-11514 2005±20 BP, Cal. 46 BC–AD 53 20–28.5 Charcoal, Alnus/Betula TRa-11513 2300±20 BP, 404–361 Cal. BC 9–20 Charcoal Sample ID C14-age, calibration (2σ) Context ID Dated material Field D 801906 1845±20 BP, Cal. AD 88–236 616349, 616346 Wood, Alnus Four cooking pits below context c. 350 Cal. BC–Cal. AD 50. Two cooking pits 616158 Charcoal dug into context c. Cal. AD 80–240 Field E 223913 TRa-11402 916±14 BP, cal. AD 1046–1165 223883, (223995) Wood 222847, TRa-11094 935±15 BP, Cal. AD 1034–1154 223002 Charcoal 223321, TRa-11101 950±20 BP, Cal. AD 1026–1155 223002 Charcoal 223323, TRa-11102 890±20 BP, Cal. AD 1046–1214 223002 Charcoal 223348, TRa-11117 1020±25 BP, Cal. AD 970–118 223002 Charcoal 222635, TRa-11308 1120±15 BP, Cal. AD 890–975 222721 Charcoal 222344, TRa-11361 2195±20 BP, 360–198 Cal. BC 222721 Charcoal 222789, TRa-11307 2205±25 BP, 361–201 Cal. BC 222721 Charcoal 223669, TRa-11122 2215±30 BP, 371–202 Cal. BC 223668 Charcoal 224815, TRa-11066 960±20 BP, Cal.